Method of forming composite metal bodies



Aug. 9, 1966 E. PRICE ETAL. 3,264,697

METHOD OF FORMING COMPOSITE METAL BODIES Filed Apri 17, 1963 I. WW, w,+77% 614.

United States Patent David E. Price, R hr bus, Ohio, assignors, by mesneassignments, to Products Co., Inc., a corporation of Delaware Filed Apr.17, 1963, Ser. No. 273,615 Claims. (Cl. 22204) This invention relates tothe forming of metal composites and in particular to the forming ofmetal composites wherein a plurality of elongated elements areintegrally associated with a surrounding matrix;

In certain applications such as in the provision of reactor rods in asuitable non-radioactive matrix medium, it is desirable to obtain apositive metallurgical bond between the matrix material and the rods atthe interface therebetween. In certain other applications such as in thepreparing of billets for use in wire drawing, wire rolling, etc., it isdeemed desirable to not only provide such a positive bond between thematrix material and the rods from which the wires are to be formed butalso to effectively preclude the attacking of the rod material by thematrix material, particularly where elevated temperatures are employedin one or more of the process steps.

The present invention comprehends an improved meth- 0d of forming such abillet or composite body wherein a matrix is effectively positivelybonded to the embedded elongated elements or rods. Thus, a principalfeature of the present invention is the provision of a new and improvedmethod of forming composite bodies.

Another feature of the invention is the provision of such a methodwherein a matrix material is effectively positively bonded to elongatedelements embedded therein.

A further feature of the invention is the provision of such a methodwherein the matrix material is eifectively prevented from attacking therod material notwithstanding the presence of high temperature conditionsduring one or more portions of the process steps.

A still further feature of the invention is the provision of such amethod wherein the matrix material is caused to flow rapidly anduniformly throughout the space in which the rods are disposed, with thespacing between the rods being effectively minimized.

A yet further feature of the invention is the provision of such a methodwherein the matrix material is introduced in molten state to form acasting about the rods, the temperature of the matrix material and therods at the time of casting being preselected as a function of the heatcapacity and dimensions of the rods and mold and the heat capacity andheat of fusion of the matrix material to cause substantiallyinstantaneous solidification of a thin layer of the matrix material onthe surface of the rods when contacted with the molten matrix materialand thereby preclude attacking of the rods by the molten matrixmaterial.

Still another feature of the invention is the provision of such a methodfurther including the step of coating the rods with a thin layer ofbonding metal.

A yet further feature of the invention is the provision of such a methodfurther including the step of coating the rods with a materialprecluding attacking of the rods by the matrix material.

A yet further feature of the invention is the provision of such a methodwherein the coating material serves both as a bonding material and anattack-preventing material.

Other features and advantages of the invention will be apparent in thefollowing description taken in connection with the accompanying drawingwherein:

FIGURE 1 is a diametric section of a casting appaice ratus and cagestructure therein as in a first step of the disclosed method of forminga composite body;

FIGURE 2 is a transverse section thereof taken substantially along theline 2-2 of FIGURE 1; and

FIGURE 3 is a side elevation of a composite body, or billet produced asby the disclosed method.

In the exemplary embodiment of the invention as disclosed in thedrawing, a composite metal body, generally designated 10, is shown tocomprise a plurality of elongated elements 11 embedded in a matrix 12.The invention comprehends a forming of the body 10 with the elongatedelements 11 firmly and positively bonded to the matrix materialuniformly along their entire lengths. The invention further comprehendsthe provision of the body 10 wherein the matrix material is cast aboutthe elongated elements 11 with attack of the elements 11 by the matrixmaterial during the casting operation being effectively precluded.

Reference now being had more specifically to FIGURE 1 of the drawing,the invention comprehends firstlly arranging a plurality of theelongated elements 11 in spaced parallel relationship in the form of acage generally designated 13. For retaining the elongated elements inthe cage, a pair of end plates 14 and 15 may be provided being suitablyperforated to receive the opposite ends of the elongated elements. Atleast one of the Plates may be suitably perforated to permit freemovement of the end of the elongated elements therein to accommolateexpansion and contraction of the elongated elements during the castingprocess.

In illustrating the invention, it will be assumed that the elongatedelements 11 comprise stainless steel rods or wires such as for use informing small diameter filaments by suitable subsequent forming of theresultant composite body, or billet, 10. As one example, the rods 11 maybe formed of A181 Type 304 stainless steel. As shown in FIGURE 2, therods are disposed herein in a uniform distribution being generallyequispaced and arranged in a symmetrical pattern. The spacing betweenthe rods is effectively minimized to permit the forming of the billetwith a minimum amount of matrix material.

The assembled cage 13 is next installed in a suitable mold 16 having acasting chamber, or cavity 1611. As shown in FIGURE 1, the top end plate14 is provided with opposed outwardly projecting lugs 14a carryingupstanding stops 14b. Herein four lugs and stops are provided spacedapart. The cage and mold are then heated by suitable means to apreselected casting temperature, herein illustratively approximately1850 F. A vacuum is drawn on the chamber 16a through a suitable outlet17 during the heating process by suitable means (not shown) toeffectively preclude attack of the stainless steel elements 11 duringthe heating step. If desired, the

vacuum may be drawn on the chamber 16a prior to the heating step and themold then scaled as by welding. If such prior evacuation is employedelevated temperature outgassing may be used. Alternatively, an inertgas, such as argon, may be introduced into the chamber 16a during theheating process to preclude the corrosion of the elements 11. It ispreferred, however, that at the time of introduction of the matrixmaterial into the cavity 164: that a vacuum condition be obtainedtherein both for facilitating the drawing of the matrix material intothe cage structure and to assure the absence of gases in the cavitywhich may form bubbles, and the like, on the elements 11 during thecasting process.

As seen in FIGURE 1, an inlet 18 is provided in the mold 16 which isnormally closed by a plug 19 sealed to the top wall 20 of the mold bymeans such as brazing 21. As shown in FIGURE 1, the top wall 20 isspaced slightly above the stops 14b. The mold may further include anmatrix material then runs down into the mold cavity 16a and through theinterstices 25 between the elements 11 to completely fill'theinterstices and bind itself firmly and positively to the elements 11along their entire lengths.

The invention comprehends the heating of the mold and cage to atemperature determined by the heat capacity and dimensions of the rodsand mold, and the heat capacity and the heat of fusion of the matrixmaterial, said temperature being such that when the matrix materialcontacts the elements 11, the portion thereof immediately surroundingthe elements substantially immediately solidifies to form a thin coatingeffectively preventing attacking of the stainless steel elements by themolten matrix material. However, the layer of solidified matrix materialcoating each element 11 issufliciently thin to preclude bridging of theinterstices 25 between the elements 11 which might otherwise precludeuniform distribution of the matrix material throughout the cage. Thetemperature to which the matrix material is heated is preselected ;as afunction of the heat absorbing'characteristics of the elements 11 andthe thermodyamic characteristics of'the matrix material including thespecific heat characteristic thereof and the heat of fusion thereof.-Further, where the mold 16 is .formed of a conductive ma-.

terial, such'as metal, the heat absorbing characteristics thereof areconsidered in determining the temperature at which the matrix materialshould be delivered to the cavity 16a. Obviously, however, the mold maybe formed of an insulating material so as to avoid heat losstherethrough and permit the rods to absorb substantially all of the heatenergy from the molten matrix material to effect the solidificationthereof.

As indicated briefly above, a quantity of nickel maybe provided in thematrix'material. The specific quantity of nickel may be preselected toadjust the working tem perature range of the matrix material to permitsubsequent working of the billet without reliquefying of the matrixmaterial. Illustratively, the matrix material may comprise a mixture of80% copper and 20% nickel 'where the elements 11 comprise AISI Type 304stainless steel. To further assure a positive bond between the matrixmaterial and the elements 11, the elements may be firstly coated with alayer 26 of a bonding metal, such as nickel, which has the property ofdissolving both in'the stainless steel and in the copper.Illustratively, a coating approximately .001 inchthick may be applied.Such a coating provides not only .an improved bond between the matrixmaterial and the elementmaterial butalso provides an effective corrosionresisting barrier further protecting the stainless steel from attack bythe copper matrix material.

The above disclosed process provides an improved billet 10 wherein theelements or rods 11 are intimately and uniformly bonded throughout theirlengths to the matrix material. Thus, the billet 10 comprises animproved billet for use in subsequent constricting operations, such ashot rolling operations wherein the billet is reduced in diameter tocorrespondingly reduce the diameter of the elements 11. Suchconstriction may be effected in successive steps until the elements 11are reduced in diameter to one mile or less. bond between the elements11 and the matrix material, discontinuities in the resultant smalldiameter filaments may be effectively minimized.

While we have shown and described one embodiment of our invention, it isto be understood that it is capable of many modifications. Changes,therefore, in the con- By providing the improved struction andarrangement'may be. made without departing from-the spiritandscope'ofthe invention as defined in the appended claims.

We claim:

1. The method of forming a composite metal body, comprising the stepsof: disposing a plurality of elongated elements in laterally spacedparallel relationship to define a cage; placingv said cage .in a moldcavity; drawing a vacuum in saidcavity; heating said cage to apreselected preheat temperature; heating a quantity of matrix material,to 'a temperature preselected as a function of the heatcapacityof saidelements andthe heat capacity and heat of 1. fusion ofv said matrixmaterial to cause substantially instantaneous solidification of a thinlayer of said matrixmaterialion' the surface of the elements whencontacted therewith;; and: introducing the heated matrix material intothe cavity to cast the matrix material about .the elongated elements ofsaid .cage .to define a billetof said elements metallurgically bonded tosaid matrix material.

2. A method of forming a composite metalbody,'corn-: prising thesteps-of: providing a plurality of elongated elements witha coating ofbonding material; disposing the plurality of ;coated elongated elements;in laterally spaced .parallel relationship to define a cage; placingsaid cage in a mold cavity; drawing a vacuum in said cavity; heatingsaid cage to a preselectedpreheat temperature; heating .a :quantity ofmatrix material to atemperature pr-eseletcedas a function of the heat:capacity of said elements and .the heat capacity and heat of fusion ofsaid matrix material to cause substantially instantaneous solidificationof a thin layer of said matrix materialon the surface vof the elementswhen contacted therewith; and introducing theheated matrix material intothe cavity to cast the matrix material about the elongated elements ofsaid cage to define a billet of said-elements metallurgically bonded tosaidmatrix material.

3. The method of claim 2 wherein said bonding mate-,

rial comprises a material soluble in the material of which the elementsare formed and in the matrix material.

4. The method of claim 2 wherein said bonding mate'-.

rial comprises a material precluding attacking of 'said elements by saidmatrix materiaLi 5.- The method of claim 2 wherein said elements areformed of stainless steel, said matrix comprises a cuprous' material,and=said bonding material comprises nickel.

6.. The method of claim 2 wherein said elements are formed of stainlesssteel, said matrix comprises a cuprous material, and saidbondingmaterial comprises; nickel deposited on saidelements in a coatingapproximately .001" deep.

7. A method of forming a composite metal body, comprising the steps .of::disposing a plurality of elongated elements in laterally. spacedparallel relationship to define acage; placingsaid cage in a moldcavity; heating said cage to a preselected preheat temperature whilepreventing attacking. cf-the elementsby air in'said cavity; heating aquantityof matrix material to a temperature preselected as a function ofthe heat capacity of said elements and the heat capacity and heat offusion of said matrix material to cause substantially instantaneoussolidification of a thin layer'of said matrix material on the surface ofthe elements when contactedtherewith; andintroducingthe heated matrixmaterial into the cavity to cast the matrix material about the elongatedelements of said cage to define ta billet. of said. elements.metallurgically bonded to said matrix material.

8. A composite metal body formed-by .the steps of:

disposing a plurality of elongated elements in laterally.

spaced parallel'relationship todefine a cage; placing said cage in amold cavity; drawing a vacuum in said cavity; heating said cage to apreselected .preheattemperature;

heating a quantity of matrix material to a'temperature preselected as afunction of the heatcapacity of aid elements and the heat capacity andheat of fusion of said matrix material to cause substantiallyinstantaneous solidification of a thin layer of said matrix material onthe surface of the elements when contacted therewith; and introducingthe heated matrix material into the cavity to cast the matrix materialabout the elongated elements of said cage to define a billet of saidelements metallurgically bonded to said matrix material.

9. A composite metal body formed by the steps of: disposing a pluralityof elongated elements in laterally spaced parallel relationship todefine a cage; placing said cage in a mold cavity; drawing a vacuum insaid cavity; heating said cage to a preselected preheat temperature;heating a quantity of matrix material to a temperature preselected as afunction of the heat capacity and dimensions of said elements and thewalls of the mold cavity, and the heat capacity and heat of fusion ofsaid matrix material to cause substantially instantaneous solidificationof a thin layer of said matrix material on the surface of the elementswhen contacted therewith; and introducing the heated matrix materialinto the cavity to cast the matrix material about the elongated elementsof said cage to define a billet of said elements metallurgically bondedto said matrix material.

10. The method of forming a composite metal body, comprising the stepsof: disposing a plurality of elongated elements in laterally spacedparallel relationship to define a cage; placing said cage in a moldcavity; heating said cage to a preselected preheat temperature; heatinga quantity of matrix material to a temperature preselected as a functionof the heat capacity of said elements and the heat capacity and heat offusion of said matrix material to cause substantially instantaneoussolidifica- 6 tion of a thin layer of said matrix material on thesurface of the elements when contacted therewith; and introducing theheated matrix material into the cavity to cast the matrix material aboutthe elongated elements of said cage to define a billet of said elementsmetallurgically bonded to said matrix material.

References Cited by the Examiner UNITED STATES PATENTS 929,777 8/1909Monnot 22204 972,630 10/ 1910 Monnot 22204 1,125,163 1/1915 Page 222031,760,583 5/ 1930 Devers 22202 2,193,246 3/ 1940 Chace 22204 2,398,5294/1946 Holmguist 22--204 2,453,772 11/ 1948 Whitfield 22204 2,543,936 3/1951 Reynolds 22204 2,611,163 9/ 1952 Schaefer et al. 22203 2,708,641 5/1955 Cape 22204 2,904,861 9/ 1959 Morgenstern 22-214 OTHER REFERENCESComposite Castings, Metal Industry, July 10, 1953, pp. 23-26 relied on.

I. SPENCER OVERHOLSER, Primary Examiner.

MARCUS U. LYONS, MICHAEL V. BRINDISI,

Examiners.

R. D. BALDWIN, Assistant Examiner.

1. THE METHOD OF FORMING A COMPOSITE METAL BODY, COMPRISING THE STEPSOF: DISPOSING A PLURALITY OF ELONGATED ELEMENTS IN LATERALLY SPACEDPARALLEL RELATIONSHIP TO DEFINE A CAGE; PLACING SAID CAGE IN A MOLDCAVITY; DRAWING A VACUUM IN SAID CAVITY; HEATING SAID CAGE TO APRESELECTED PREHEAT TEMPERATURE; HEATING A QUANTITY OF MATRIX MATERIALTO A TEMPERATURE; PRESELECTED AS A FUNCTION OF THE HEAT CAPACITY OF SAIDELEMENTS AND THE HEAT CAPACITY AND HEAT OF FUSION OF SAID MATRIXMATERIAL TO CAUSE SUBSTANTIALLY INSTANTANEOUS SOLIDIFICATION OF A THINLAYER OF SAID MATRIX MATERIAL ON THE SURFACE OF THE ELEMENTS WHENCONTACTED THEREWITH; AND INTRODUCING THE HEATED MATRIX MATERIAL INTO THECAVITY TO CAST THE MATRIX MATERIAL ABOUT THE ELONGATED ELEMENTS OF SAIDCAGE TO DEFINE A BILLET OF SAID ELEMENTS METALLURGICALLY BONDED TO SAIDMATRIX MATERIAL.